Age-related hypermethylation of the hMLH1 promoter in gastric cancers.

To determine whether methylation of the hMLH1 promoter is related to increasing age and gastric carcinogenesis, we examined hMLH1 methylation and expression in 100 gastric cancers. hMLH1 methylation and aberrant protein expression were observed in 9 and 13 cancers, respectively. Normal and intestinal metaplastic tissues adjacent to cancers with hypermethylation did not exhibit any hMLH1 methylation, indicating that it may be specific to gastric cancers. The frequency of hMLH1 methylation significantly increased with age. These results suggest that hMLH1 methylation plays an important role in gastric carcinogenesis in old people.